Implantable infusions systems have been used to treat a variety of diseases, such as spasticity, pain and cancer by targeting drug delivery to a selected area of a patient. Therapies employing such systems have proven to be very helpful for patients for which systemic therapy is not effective, possible, or practicable. The implantable systems typically include an implantable infusion device containing a reservoir for housing the drug and a catheter coupled to the reservoir to direct the drug to the target area. The devices typically include a pump or mechanism for driving fluid from the reservoir, or withdrawing fluid from the reservoir, and through the catheter.
Most implantable infusion devices closely control the rate at which the drug is delivered to ensure that the patient receives an appropriate dose of the drug. However, there may be instances in which inappropriate dosing (e.g., under-dose or overdose) occurs. Many current devices have electronics or sensors that allow for monitoring of malfunctions, such as battery depletion or stalling of the pump. Some infusion devices have been proposed that are capable of monitoring catheter complications, such as a leak, a dislodgement, or an occlusion. Upon detection of an infusion device or catheter malfunction or the likelihood of such a malfunction, the device may alert the patient to seek medical attention. The malfunction event may be stored in device memory and may be retrieved by a healthcare provider upon a patient visit so that the nature of the malfunction can be ascertained by the healthcare provider.
However, infusion device or catheter malfunctions are not the only source of inappropriate dosing. In some instances, the infusion device may be programmed or set to deliver the drug at a rate that is too high or too low for the therapy that the patient is receiving; a particular patient may not respond, or may be too sensitive, to a given drug relative to the general population; the concentration of the drug introduced into the reservoir may be higher or lower than intended or appropriate; etc. In such cases, the infusion device and catheter may be perfectly functional, but the patient does not receive a dose of the drug that is appropriate for the therapy. In these cases, it can be difficult to identify the source of the inappropriate dose or even that an inappropriate dose has been, or is being, delivered.
For example, a healthcare provider may interrogate the infusion device to determine the drug infusion parameters. However, if the healthcare provider is the one who set the parameters initially, the parameters may appear perfectly appropriate. In addition, it may not be readily apparent in all cases which of the patient's symptoms are indicative of an under- or overdosing of the drug.